Woodboring tool



W. MCMAHON wooDBoRING TOOL Oct. 1, 1935.

Filed May 24, 1934 Patented Oct. 1, 1935 UNITED STATES WOODBORIN G TOOL William McMahon, Lidcombe, near Sydney, New

, South Wales, Australia Application May 24, 1934, Serial No. 727,344 In Australia February 19, 1934 3 Claims.

This invention relates to tools for woodworking, and the object thereof is to provide a tool for the formation of square or other cornered recesses or apertures in wood, or for the formation of squared ends to elongated recesses or apertures as in mortise work.

In order to fully describe the invention reference is made to the accompanying drawing which depicts an embodiment suitable for forming square holes, and in which Figure 1 is a perspective view of the tool,

Figure 2 a longitudinal cross-sectional elevation thereof on plane 2 2 of Figure 1,

Figure 3 a longitudinal fragmentary cross-sectional elevation of. the tool, during operation, taken on the plane 3 3 of Figure l, at right angles to the section of Figure 2,

Figure 4 a cross-sectional view taken on line 4 4 of Figure 3, shewing a detail,

Figure 5 a fragmentary perspective view shewing a modication, and

Figure 6 a longitudinal cross-sectional elevation taken on plane 6 6 of Figure 5.

The tool illustrated in Figures l, 2, 3, and 4 includes an elongated punch of square external section and with a cylindrical bore 2 formed therethrough. The lower end of punch I is formed with cutting edges 3 to punch a square aperture through the woodwork. Chip escape apertures 4, 4 are formedthrough opposite sides of the punch, and at the upper end a collar 5 is threaded thereon.

A woodboring twist-bit 6 is neatly mounted for rotation in the internal bore 2 of the punch, the lower end l of the bit projecting slightly past the cutting edges 3 of the punch. A collar 61 is formed on the bit just above chip apertures ll, to force the chips through said apertures.

The upper end 8 of the bit 6 projects through the upper end of the punch I and collar 5, where the cylindrical lower end 91 of a bit-head 9 is threaded thereon. The diameter of the cylindrical bit-head 9 is increased at its upper end I0 with the formation of a shoulder II, and a tapered chuck engaging shank head I2 is formed on the extreme upper end thereof.

A hollow cylindrical hammer I3 is mounted about the bit-head 9 for longitudinal and rotational oscillation thereon, the internal bore of the hammer being a neat sliding t on the larger diameter I0 of the bit-head, and an internal ange I4 at the lower end of the hammer being a sliding fit on the smaller section 91 of the bithead.

A compression coil spring I5 is located between the smaller section 91 of the bit-head and the surrounding hammer I3, the spring bearing at its ends respectively upon the shoulder I I of the bithead and the ange lI4 of the hammer, and thus operating to force the lower end of the hammer 5 against the shoulder 5 on the punch I. A guide pin I6 threaded into the lower end of hammer i3, and passing through an aperture I'I in flange 5 of the punch I prevents rotation of the hammer in relation to the punch, but does not im- 10 pede longitudinal oscillation in relation to the same. v

A cam track is formedin the larger section I0 of the bit-head 9, the track consisting a gradually rising portion I8 which terminates in a ver- 15 tical drop section I9. This cam track is duplicated, diametrically opposite on section I0, by rising portion |81 and vertical drop section |91. A set screw Z0 is threaded through the wall of hammer I3 and the nose 2| of this set screw en- 20 Y gages in the cam track. The set screw is duplicated at 201, diametrically opposite in the hammer I3.V

In order to permit reverse rotation of bit 6 independently of the punch I to facilitate dis- 25 engagement from the wood after boring has terminated, a clear annular recess |01 is formed in portion I0 immediately above the apexes of the cam tracks I8 and |81. To effect such reversal, hammer i3 is retracted to the position shewn in 30 Figure 3, when the set screws 20 and 201 register with the annular recess |01, and the bithead 9 with its cam tracks may be reversed without interference from the set screws.

In order to provide means to readily maintain 35 the hammer 9 in this retracted position during reversal of the bit, a shallow arcuate recess 2| is formed in the upper face of shoulder 5, and in communication with aperture I1 (Figure 4). y When it is desired to retain the hammer I3 in 40 retracted position it is simply rotated slightly from this position to bring the nose of pin I6 in recess 2|, where it remains during reversal of the bit, and whence it is released by a partial turn of the hammer to once more align pin I6 45 with its slot Il. l

The operation of the tool is as follows:

The shank head I2 of the bit-head is introduced into a drill (or brace) and the nose of the tool is applied to the woodwork. The punch is manu- 50 ally held against rotation and the drill is rotated, causing the bit head 9 and the bit 6 to similarly rotate and the latter to bore into the woodwork. As the bit-head revolves, the engagement of the noses of set screws20 and 201 in the cam tracks I8 55 and |81 causes the hammer I3 to slide longitudinally on the bit-head 9 and to be retracted from the collar 5 (as shewn in Figure 3) compressing spring I5: in this figure the set screw 201 is shewn to have just risen to the apex of cam track |81 and to be about to drop down vertical section |91. When the vertical drop sections I9 and I91 of the cam track reach the set screws, the spring I5 snaps the hammer I3 down on the collar 5, delivering a Y heavy impact blow to the punch I and causing the sharpened edges 3 of the same to bite into the woodwork and shape the round hole drilled by the bit 5 into a neat square hole. The chips from the bit and punch I are discharged through the apertures 4, IlA in the punch.

During each revolution of the bit 6 the hammer i I3 will rise and fall twice, the number of vertical drop sections of the cam track (such as I9 and |91) obviously determining the number of blows imparted by the hammer I3 to the punch I during eachY such revolution.

In certain cases, such as when the tool is being constantly used on hardwood, it may be necessary to renew the punch I. To facilitate and cheapen such renewal, the nose of the punch may be detachable, as shewn in Figures 5 and 6. The nose 24 of the punch is square, as heretofore, and at its upper end 25 is internally threaded and screws on to an external thread on the lower end 29 of a hollow cylindrical punch tube 21 and abuts against a collar 28 on said tube.

The bit 5 is normal at its lower end, but is reduced in diameter at 29 where it lies within the smaller internal diameter of the punch tube 2l. By means of this construction the nose 24 is detachable and consequently renewable at lower cost than would be the whole punch I of the construction shewnV in Figures 1, 2, and 3.

I claim:

l. A woodboring tool comprising a hollow punch with a sharpened extremity, a woodboring bit rotatably mounted within said punch, a hammer slidably mounted in relation to said punch, cam

means actuated by rotation of the bit for retracting said hammer in relation to said punch, and a spring adapted to move said hammer from such retracted position to impart a blow to said punch during said rotation of the bit.

2. A woodboring tool comprising a hollow punch of rectangular external section and with a cylindrical bore therethrough, a shoulder on said punch remote from the operative end thereof, a woodboring bit rotatably mounted in said bore and passing through said shoulder, a bit-head secured on said bit, a cylindrical hammer axially reciprocable in relation to said punch and having rotational and reciprocable bearing on the bit-head, a spring urging said hammer into contact with said shoulder, and means including a cam track actuated by rotation of the bit-head in relation to the punch to retract said hammer from said shoulder and to permit the spring to return the hammer against said shoulder to impart a blow to the punch during the said rotation of the bit.

3. A woodboring tool comprising an elongated punch of square external section formed with a cylindrical bore therethrough, a cutting edge on one end of said punch and a shoulder on the other end, a woodboring bit rotatably mounted within said bore and protruding through said shoulder, a bit-head secured on the bit outside said shoulder, a cylindrical hammer slidably and rotatably mounted on said bit-head and adapted to contact with said shoulder, means for restraining rotation of said hammer in relation to said punch, a spring urging said hammer into contact with said shoulder, and a cam track formed in said bithead and engaged by an element in said hammer for the purpose of retracting said hammer from said shoulder during rotation of the bit in relation to the punch, characterized in that a portion of said cam track is formed to permit the spring to return the hammer to the shoulder from the retracted position.

WILLIAM McMAI-ION. 

